I'm on Fiber from Sonic and last week I was experiencing issues with connections randomly being dropped and being extremely slow to load. Sonic tech came out and said that the uplink was good and that it might be a problem with my UniFi system, but I don't have any issues with my LAN services.
It's great that the community was able to diagnose this, but a shame that AT&T didn't pick it up first and isn't acknowledging an issue on their network.